Piston by-pass valve



May 2D 1924.'

1,494.972 J. A. PFEIFFER PlsToN BY-PASS VALVE Filed Sept. 5. 1919 5Sheets-Sheet 1 May 20, 1924.

. J. A. PFEIFFER PI STON BY- PASS VALVE' .5 Sheets-Sheet Z Filed Sept;6. l9l9 May 20, 1924.

J. A. PFEIFFER PISTON BY-PASS VALVE F''led Sept. 6, 1919 I5 Sheets-Sheet3 provenients are illustrated Patented May Z0, 19224.

UNITED sTArss JoHN A. PFEIFFER, or PHILADELPHIA, PENNSYLVANIA.

PISTON BY-PASS VALVE.

Application filed September 6, 1919., Serial No. 322,104.

To all whom t may concern Be it known that I, JOHN A.. PFEIFFER, acitizen of the United States, residing in Philadelphia, Pennsylvania,have invented a Piston By-Pass Valve, of which the following is aspecification.

This invention relates tol piston by-pass valves, such as are employedwith the' piston valves of steam engines for automatically relievingexcessive back pressure, resulting from various causes, inthe' cylinderof said engine. A `relief mechanism of this type-furnishes the subjectmatter of my former United States Patent No. 910,851, dated January 26,1909, and 'my present invention consists of certain l improvements uponthis typel of relief mechanism and in the addition of certain novelfeatures which will be described hereinafter.

Piston by-pass valves embodying my imin theattached drawings, in which:Y

Fig. 1 is a vertical, longitudinalv section of a piston valve comprising4my by-pass valve, and'of a portion of the valve casing in which thesaid valve operates;

F ig. 2 is a vertical section of the piston yvalve taken on the line a-ao-f Fig. 1;

Fig. v3 is a detached vsectional view of a portion of the pist-on valveillustrating the details ofthe valve structure of the type used withsuper-heated steam; v

Fig. 4 is a detached view similar to the View of Fig. 3, butillustrating the yby-pass valveadapted to use with `saturated steam;

Figs. 5 and 6 are detached views similar to views of Figs. 3 and 4,illustrating a modification iof the bypass valve as employed with pistonvalves having inside and outside admission respectively.

Referring to the drawings, 1 indicates that portion ofy the cylindercastings of a locomotive forming the -valve chamber, 2,

'in which a piston valve; 3,V reciprocates.

vInlet ports, 4, are formed in thewalfs of the valve chamber, 2, throughwhich steam is admittedto' said chamber froina steam passage, 5, whileports 6 and '7 openinto passages 8 and 9 respectively, 'leading toopposite ends of the engine cylinder.` Exhaust ports, 10 and 11 giveaccess fromv the interior of the .said valve chamber to exhaust passages12 and 13 respectively. y .l I The pistonl valve 3, comprises a hollowbody, 14, and bull-rings, 15, intermediate rings,.16, and followers, 17,at each end of the piston valve said followers being mounted upon andsecured to a shaft, 18, and the bull-rings, 15, and intermediate rings,16, being interposed between the hollow body member, 14, and the saidbull-rings; Piston rings, 19, 19, are provided at 'each end of thepiston valve.` Located in the bull-rings at various points around thecircumference thereof 'is a series of Lesliaped passages, 20, extendingfrom the periphery of-said rings to the side surface abutting theintermediate rings, 16. The intermediate rings, 16, have apertures, 21,therein corresponding in' number and positionr with the apertures, 20,in.

the bull-riiigs, the said intermediate rings having also a series ofapertures, 22, there 4in leading from the outer surface of said ing theapertures, l21, while the other -leg covers the aperturer22.` TheL-shaped yring valve is adapted to slide upon the outer surface of theintermediate rings, 16, and packing rings, 24, are located upon theintermediate rings and act against the inner surface of the valve ring,23. Located at each endr of the hollow body'membe'r, 14,

is a series of outwardly extending lugs, 25,l said lugs being spacedaround the circumference of said body member and each being apertured at26 to receive apiston pin,

27. rIhe piston pins, 27, vhave a. shoulder, 28, formed thereon, and aspring, 29, is interposed between said shoulder and the shoulder 25aformed upon the said lugs,25, whereby said piston pins, 27, areforcedoutwardly against the sides yofthe said ring valves, 23, thesprings tending to hold said piston valves to their seats, closing theapertures 21 and 22. ,j .y

The operation of the .device isy as follows:

The ring valves, 23, are normally held totheir seats, closing theapertures 21 and 22, by the pressure ofthe live steam entering thelvalve chamber, 2, through the passage, 5, leading fromy the lsteampipe,A and also by the pressure, of the springs, 29, exerted through thepins, 27. Should the back pressure in the cylinder of the engine becomeeX- cessive due to the compression of steam, or

water in the cylinder by the movement of the piston therein, or for anyother reason, the piston rings 23 will be forced back by the saidexcessive back pressure acting through the passages, 20, in thebull-rings and the apertures, 2l, in theV intermediate rings, saidbackward position of the piston ring being indicated in broken lines inFig. 3. In this position the passages 2l and 22 are uncovered by thevalve ring thereby opening up passages between the cylinder of theengine, the steam chest, and the exhaust. Under these conditions theexcessive pressure in the cylinders is immediately relieved and ageneral balance of pressure in the entire engine obtained. Following thereduction of the pressure in the cylinder, the valve ring, 23, under theIpressure of the steam and springs, 29, will return immediately vto the`forward position covering the passages 21 and 22.

In Fig. 4 I have illustrated my relief mechanism adapted to use inengines employing saturated steam, in which no driftving valve isprovided. The details of construction are similar in all respects tothose already describedl with the exception that the force of thespring, 29a, is brought to bear upon the outer surface of the valverings, 23, through the kpins 27a. In this case the pins 27a and thesprings 29a are mounted in apertures, 30, extending through thebull-rings and through the intermediate rings, 16, the tendency `of thesprings being to force the kring valves away from their seats coveringthe passages 2l and 22, and thereby form a by-pass to either end ofcylinder when steam is cut olf and `engine drifting. The pressure of thesprings 29"VL upon the rings, 23, is such as to prevent any vibration ofthe ring valve after the excessive back pressure has forced said valvefrom its seat, the valve being held to its seat by the pressure of thelive steam coming from the steam chest of the engine.

It is obvious that the construction described may bemodified in numerousrespects with no departure from the essential features of the invention.

In the modifications illustrated in Figs. 5 and 6, I have shown a pistonvalve equipped with my by-pass valve and particularly adapted to lowspeed engines. The piston valve shown in Fig. 5, consists o-f a y hollowcylindrical body, 31, formed of steel tubing or thelike, which extendsthrough the length of the valve and near each end of which is attachedby means, in the present case, of rivets, y32, an L-shaped backingflange, 33. Between the flange, 33, and the follower, 34, one of whichis attached at each end of the body, 31, in the usual manner, is carrieda bull-ring, 35, provided with an annular recess, 36, in which islocated a ring valve, 37. Packing rings 38" and 39 are provided in thebull-ring and on the said ring valve, 37, respectively, while lthepiston rings 40 and 4l are located in the usual manner between thebull-ring and the follower and flange 33 respectively at each end of thepiston valve. Passages 42 and 43, a series of which extend around thewhole circurn ference of the bull-ring, extend from the said annularrecess, 36, to the outer and inner surfaces of the said bull-ringrespectively. A series of holes, 44, corresponding with the holes `43 inthe bull-ring, is formed in the tubular body, 3l, while a further seriesof apertures, 45, is formed in the backing flange, 33, and gives accessfrom the space around the outsideof the tubular body, 3l, to the annularrecess, 36. This valve is of the insideadmission type, the ring valve:being held to its seat by the pressure of the live steam from the steamchest operating through the apertures, 45. When seated, the ring valvecloses the passages 42 and 43, as shown, but when forced back byexcessive pressure in the engine cylinder the passages 42 and 43 areunited and the excess pressure is accordingly lrelieved intov theexhaust 4 the outside admission type, the construction Y is in generalvsimilar to the valve of Fig. 5, with the exceptions that the positionsof the bull-ring and ring valve are substantially reversed, the pressureofthe live steam in holding the ring valve 37a toits seat being exertedthrough a series of holes, 46, formed in the follower, 34a. In this casethe passages 42a, 43a, corresponding to the passages 42 and 43 of Fig.V`5, connect with the apertures 45a in the flange 33a. In this manner,when the ring valve is forced from itsy seat the excessive pressure isrelievedinto the ex- ,y aust, which is desirable,A particularly inhighspeed engines.

In an engine utilizing my by-passv device there can be no breaking ofthe cylinders, nor knocking out of cylinder heads due to excessive backpressure in the cylinders, nor

are any of the other accidents, Ywhich atpresentare known to arise'fromexcessive compression, or improperly set valves such as the breaking ofthe frames `between the cylindersand main pedestal, the bending of themain rods, or the development off knocks in themain boxes with aconsequent tendency to heat main journals', possible. Furthermore avalve equipped with my by-pass will not suck gases and cinders from thesmoke-box through the exhaust pipe into the cylinder when the engine isdrifting with a consequent cutting olf the valve seat and cylinders,this being due to the fact that the said ring valves will open whendrifting, thereby establishing anuinobstructed passage between both endsof the cylinder and the exhaust chamber and steam chest, with aresulting equalization of pressure throughout.

I claim:

l. A piston Valve comprising a pair of substantially ring-shaped pistonshaving extending therebetween a tubular body, Whereby a longitudinalpassage is formed through said valve from end to end thereof, saidpistons having passages extending from the peripheries thereof .to theinner opposed faces, ports 'forming communication between the saidlongitudinal passage and the space outside of the said body and betweenthe pistons, and relief Valves adapted to close the said ports andpassages at each end of said piston valve.

2. In a steam engine, the combination with a valve chamber, of ductsextending 20 from said valve chamber to a source of steam supply, to theexhaust and to each end of the cylinder of saidengine, a piston kvalvein said Valve chamber comprising a pair of substantially ring-shapedpistons havin eX- tending therebetween a tubular body, W 1ereby alongitudinal passage is formed through the piston valve establishingcommunication between the ends of said valve chamber, said pistonshaving passages therein whereby communication may be established betweenthe said cylinder ducts and the space outside of said body and betweenthe said pistons, ports at each end of said piston valve establishingcommunication between the said space outside of said body and betweenthe said pistons and the ends of said valve chamber, and a relief valveadapted to close said ports and passages at each end of ksaid pistonValve.

JOHN A. PFEIFFER.

